Backlight unit and display apparatus using the same

ABSTRACT

Disclosed are an illumination system and a display apparatus using the same. The illumination system includes a light guide plate; grooves disposed in the light guide plate, each of the grooves having at least one inclined surface; light source modules disposed within the grooves, wherein the light source modules comprise, substrates and light sources disposed on the substrates; and stoppers disposed between a first surface of each of the light sources and the at least one inclined surface of each of the grooves, the first surface of each of the light sources facing the at least one inclined surface. A cross-sectional area of the grooves is larger than that of the stoppers.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation of copending application Ser. No.13/414,366, filed on Mar. 7, 2012, which claims the benefit under 35U.S.C. §119 to Korean Patent Application No. 10-2011-0061716, filed inKorea on Jun. 24, 2011 and No. 10-2011-0070377, filed in Korea on Jul.15, 2011 all of which are hereby expressly incorporated by referenceinto the present application.

TECHNICAL FIELD

Embodiments relate to a backlight unit and a display apparatus using thesame.

BACKGROUND

In general, as a representative large-scale display apparatus, a liquidcrystal display (LCD) or a plasma display panel (PDP) is used.

Differently from the PDP of a self-emitting type, the LCD essentiallyrequires a separate backlight unit due to absence of self-emitting lightemitting devices.

Backlight units used in LCDs are divided into an edge type backlightunit and a direct type backlight unit according to positions of lightsources. In the edge type backlight unit, light sources are disposed onside surfaces of an LCD panel and a light guide plate is used touniformly distribute light throughout the overall surface of the LCDpanel, and thus uniformity of light is improved and the panel has anultra-thin thickness.

In the direct type backlight unit which is generally used in displayshaving a size of 20 inches or more, a plurality of light sources isdisposed under a panel. Thus, the direct type backlight unit hasexcellent optical efficiency, as compared to the edge type backlightunit, thereby being mainly used in a large-scale display requiring highbrightness.

As light sources of the conventional edge type or direct type backlightunit, cold cathode fluorescent lamps (CCFLs) are used.

However, a backlight unit using CCFLs may consume a considerable amountof power because power is applied to the CCFLs at all times, exhibit acolor reproduction rate of about 70% that of a CRT, and causeenvironmental pollution due to addition of mercury.

In order to solve these problems, research into a backlight unit usinglight emitting diodes (LEDs) has been conducted.

If LEDs are used as the backlight unit, an LED array may be partiallyturned on/off and thus power consumption may be considerably reduced.Particularly, RGB LEDs exceed 100% of national television systemcommittee (NTSC) color reproduction range specifications, thus providinga more vivid image to consumers.

SUMMARY

Embodiments provide a backlight unit which stably fixes light sourcemodules using stoppers having a designated shape and fastening membersthereof, and a display apparatus using the same.

In one embodiment, a backlight unit includes a light guide plate,grooves disposed in the light guide plate, the grooves having at leastone inclined surface, light source modules disposed within the grooves,and stoppers disposed between the light source modules and the lightguide plate, wherein a cross-sectional area of the grooves is largerthan that of the stoppers.

The stoppers may be disposed within the grooves of the light guide plateand contact at least one of the side surfaces of the grooves, the bottomsurfaces of the grooves and the light source modules.

The stoppers may be disposed within the grooves of the light guideplate, be separated from the side surfaces of the grooves at a firstinterval, be separated from the bottom surfaces of the grooves at asecond interval, and be separated from the light source modules by athird interval.

The first interval may be greater than the second and third intervals,and the third interval may be smaller than the first and secondintervals.

The stoppers may be attached to substrates of the light source modulesby an adhesive agent.

The stoppers may be attached to the bottom surfaces of the grooves ofthe light guide plate by an adhesive agent.

The stoppers may be simultaneously attached to substrates of the lightsource modules by a first adhesive agent and the bottom surfaces of thegrooves of the light guide plate by a second adhesive agent.

The first adhesive agent and the second adhesive agent may be formed ofdifferent materials.

A reflector may be disposed on at least one of the side surfaces and thebottom surfaces of the grooves of the light guide plate.

The shape of the stoppers may be varied according to the shape of thegrooves on the light guide plate, and be formed of a polymer resin whichenables injection molding, particularly of at least one of unsaturatedpolyester, methyl methacrylate, ethyl methacrylate, isobutylmethacrylate, n-butyl methacrylate, acrylic acid, methacrylic acid,hydroxyl ethyl methacrylate, hydroxyl propyl methacrylate, hydroxylethyl acrylate, acrylamide, ethyl acrylate, isobutyl acrylate andn-butyl acrylate.

Each of the grooves of the light guide plate may include a first sidesurface and a second side surface opposite each other, the first sidesurface of each of the grooves may be perpendicular to the bottomsurface of each of the grooves, and the second side surface of each ofthe grooves may be inclined with respect to the bottom surface of eachof the grooves.

Each of the grooves of the light guide plate may include a first sidesurface and a second side surface opposite each other, the first andside surfaces of each of the grooves may be inclined with respect to thebottom surface of each of the grooves, and an inclination angle betweenthe first side surface and the bottom surface of each of the grooves maybe smaller than an inclination angle between the second side surface andthe bottom surface of each of the grooves.

Further, the grooves of the light guide plate may have a triangularcross-section, and an angle between first and second side surfacesopposite each other of each of the grooves may be about 30° to 120°.

Further, a ratio of the height of the grooves of the light guide plateto the overall thickness of the light guide plate may be about0.3˜0.7:1.

In another embodiment, a backlight unit includes a light guide platehaving grooves, light source modules disposed within the grooves of thelight guide plate, stoppers disposed between the light source modulesand the light guide plate, stopper fastening parts disposed on the lowersurface of the light guide plate, and connection members disposed on thelower surfaces of the stoppers and connected to the stopper fasteningparts.

The stopper fastening parts may be disposed at positions adjacent to thegrooves of the light guide plate, or may be disposed between lightsources of the light source modules.

The stopper fastening parts may be projections protruding from the lowersurface of the light guide plate or depressions disposed on the lowersurface of the light guide plate.

The stopper fastening parts may have one planar shape of a circle, ahemisphere, a triangle, a rectangle and a polygon.

The stopper fastening parts may be formed of a material differing fromthe light guide plate, and may be formed of one selected from among thegroup consisting of polymethylmethacrylate (PMMA), polyethyleneterephthalate (PET), cyclic olefin copolymers (COCs), polyethylenenaphthalate (PEN), polycarbonate (PC), polystyrene (PS) and methacrylatestyrene (MS) resins.

The stopper fastening parts may have the same thickness as theconnection members, or may have a greater thickness than the connectionmembers.

The side surfaces of the stopper fastening parts and the side surfacesof the grooves of the light guide plate may be located on the sameplane.

Each of the connection members may include a body portion supporting thestopper and the light source module and a connection portion protrudingfrom the body portion and connected to the stopper fastening part.

The connection portion may include a first segment protruding from thebody portion and a second segment extending from the end of the firstsegment and having a greater area than the first segment.

Here, the thickness of the first segment may be greater than thethickness of the body portion and be equal to thickness of the secondsegment, or the thickness of the first segment may be greater than thethicknesses of the body portion and the second segment and the thicknessof the second segment may be equal to the thickness of the body portion.

At least one connection portion may be provided and one connectionportion may be connected to one stopper fastening part one to one, or aplurality of connection portions may be provided and a pair ofconnection portions may be disposed between adjacent stopper fasteningparts.

The connection portion may include a first segment protruding from thebody portion and a second segment extending from the end of the firstsegment and having a greater area than the first segment.

The planar shape of the first and second segments may be equal to theplanar shape of the stopper fastening parts.

BRIEF DESCRIPTION OF THE DRAWINGS

Arrangements and embodiments may be described in detail with referenceto the following drawings in which like reference numerals refer to likeelements and wherein:

FIG. 1 is a cross-sectional view illustrating a backlight unit inaccordance with one embodiment;

FIGS. 2 and 3 are cross-sectional views illustrating stoppers disposedwithin grooves of a light guide plate of FIG. 1;

FIGS. 4A to 4D are cross-sectional views illustrating stoppers attachedto a light source module and the light guide plate;

FIGS. 5A to 5C are cross-sectional views illustrating shapes of grooveson the light guide plate;

FIGS. 6A and 6B are cross-sectional views illustrating positionrelations between the groove of the light guide plate and the lightsource module;

FIG. 7 is a cross-sectional view illustrating a backlight unit inaccordance with another embodiment;

FIGS. 8 and 9 are cross-sectional views illustrating stoppers disposedwithin grooves of a light guide plate;

FIG. 10 is a structural cross-sectional view illustrating connectionbetween a connection member and a stopper fastening part in accordancewith a first embodiment;

FIG. 11A is a bottom perspective view illustrating the stopper fasteningpart of FIG. 10;

FIG. 11B is a bottom perspective view illustrating the connection memberof FIG. 10;

FIG. 11C is a bottom perspective view illustrating connection betweenthe connection member and the stopper fastening part of FIG. 10;

FIG. 12 is a structural cross-sectional view illustrating connectionbetween a connection member and a stopper fastening part in accordancewith a second embodiment;

FIG. 13A is a bottom perspective view illustrating the connection memberof FIG. 12;

FIG. 13B is a structural cross-sectional view illustrating theconnection member of FIG. 13A;

FIG. 14 is a structural cross-sectional view illustrating connectionbetween a connection member and a stopper fastening part in accordancewith a third embodiment;

FIG. 15A is a bottom perspective view illustrating the connection memberof FIG. 14;

FIG. 15B is a structural cross-sectional view illustrating theconnection member of FIG. 15A;

FIG. 16A is a bottom perspective view illustrating a stopper fasteningpart in accordance with a fourth embodiment;

FIG. 16B is a bottom perspective view illustrating a connection memberin accordance with the fourth embodiment;

FIG. 16C is a bottom perspective view illustrating connection betweenthe connection member and the stopper fastening part in accordance withthe fourth embodiment;

FIG. 17A is a bottom perspective view illustrating a stopper fasteningpart in accordance with a fifth embodiment;

FIG. 17B is a bottom perspective view illustrating a connection memberin accordance with the fifth embodiment;

FIG. 17C is a bottom perspective view illustrating connection betweenthe connection member and the stopper fastening part in accordance withthe fifth embodiment;

FIG. 18 is a plan view illustrating an area in which a stopper fasteningpart in accordance with one embodiment is disposed;

FIG. 19 is a cross-sectional view illustrating a display module having abacklight unit in accordance with one embodiment; and

FIGS. 20 and 21 are views respectively illustrating display apparatusesin accordance with embodiments.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Hereinafter, embodiments will be described with reference to the annexeddrawings.

It will be understood that when an element is referred to as being “on”or “under” another element, it can be directly on/under the element, andone or more intervening elements may also be present.

When an element is referred to as being “on” or “under”, “under theelement” as well as “on the element” can be included based on theelement.

FIG. 1 is a cross-sectional view illustrating a backlight unit inaccordance with one embodiment.

As shown in FIG. 1, the backlight unit includes a light guide plate 20,a reflector 30, optical members 40, light source modules 50, andstoppers 70.

The backlight unit may further include a top chassis 60, a bottomchassis 10, and a panel guide module 80.

Here, the panel guide module 80 may support a display panel 90, and thetop chassis 60 may be connected to the panel guide module 80 and thebottom chassis 10.

Then, at least one groove 24 may be disposed on the lower surface of thelight guide plate 20, and the optical members 40 may be disposed on theupper surface of the light guide plate 20.

Here, the grooves 24 of the light guide plate 20 may have a triangular,rectangular, or trapezoidal cross-section.

If the grooves 24 of the light guide plate 20 have a trapezoidalcross-section, from among first side surfaces and second side surfacesof the grooves 24 opposite each other, the first side surface of thegroove 24 may be perpendicular to the bottom surface of the groove 24,and the second side surface of the groove 24 may be inclined withrespect to the bottom surface of the groove 24.

Otherwise, if the grooves 24 of the light guide plate 24 have atrapezoidal cross-section, the first and second side surfaces of thegroove 24 opposite each other may be inclined with respect to the bottomsurface of the groove 24, and an angle between the first side surfaceand the bottom surface of the groove 24 may be smaller than an anglebetween the second side surface and the bottom surface of the groove 24.

Further, if the grooves 24 of the light guide plate 20 have a triangularcross-section, an angle between first and second side surfaces oppositeeach other of the groove 24 may be about 30° to 120°.

Further, a ratio of the height of the grooves 24 of the light guideplate 20 to the overall thickness of the light guide plate 20 may beabout 0.3˜0.7:1.

The light guide plate 20 may be formed of one selected from among thegroup consisting of acrylic resins, such as polymethylmethacrylate(PMMA), polyethylene terephthalate (PET), cyclic olefin copolymers(COCs), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene(PS) and methacrylate styrene (MS) resins.

The light source modules 50 may be disposed within the grooves 24 of thelight guide plate 20.

Here, each light source module 50 may include a substrate 54 and atleast one light source 52 disposed on the substrate 54. Both thesubstrate 54 and the at least one light source 52 may be disposed withinthe groove 24 of the light guide plate 20.

According to circumstance, the substrate 54 may be disposed at theoutside of the groove 24 of the light guide plate 20, and the at leastone light source 52 may be disposed within the groove 24 of the lightguide plate 20.

The substrate 54 may include an electrode pattern to be electricallyconnected to the light source 52, and may be a printed circuit board(PCB) formed of one selected from the group consisting of polyethyleneterephthalate (PET), glass, polycarbonate (PC) and silicon (Si), or beformed as a film.

Further, the substrate 54 may selectively employ a single layer PCB, amulti-layer PCB, a ceramic substrate, a metal core PCB, etc.

The at least one light source 52 may be disposed on the substrate 54,and the light source 52 may be a side view type LED.

According to circumstance, the light source 52 may be a top view typeLED.

As described above, the light source 52 may be an LED chip, and the LEDchip may be a blue LED chip or an ultraviolet LED chip, or a package inwhich at least one of a red LED chip, a green LED chip, a blue LED chip,a yellow green LED chip and a white LED chip are combined.

Here, the white LED may be produced by combining a yellow phosphor witha blue LED, by using both a red phosphor and a green phosphor on a blueLED, or by using a yellow phosphor, a red phosphor and a green phosphoron a blue LED.

The reflector 30 may be disposed on the lower surface of the light guideplate 20.

That is, the reflector 30 may be disposed between the light guide plate20 and the bottom chassis 10, and may extend from the lower surface tothe side surface of the light guide plate 20.

Here, the reflector 30 is not disposed on the lower surface of thesubstrate 54 of the light source module 50. However, according tocircumstance, the reflector 30 may be disposed on the lower surface ofthe substrate 54.

Further, the reflector 30 may be disposed on at least one of the sidesurfaces of the grooves 24 of the light guide plate 20 and the bottomsurfaces of the grooves 24.

Here, the reflector 30 may be formed of at least one of a metal and ametal oxide, and for example, may be formed of a metal or a metal oxideexhibiting high reflectivity, such as aluminum (Al), silver (Ag), gold(Au) or titanium oxide (TiO₂).

The optical members 40 may be disposed on the upper surface of the lightguide plate 20.

Here, the optical members 40 serve to improve optical characteristics oflight emitted through the light guide plate 20, and may have an unevenpattern disposed on the upper surface thereof to increase diffusioneffects.

Further, the optical members 40 may include several layers, and theuneven pattern may be disposed on the surface of the uppermost layer orone layer.

The uneven pattern may have a stripe shape disposed along the lightsource modules 50.

Here, the uneven pattern includes protrusions protruding from thesurface of the optical member 40, and the protrusions include firstplanes and second planes opposite each other. An angle between the firstplane and the second plane may be obtuse or acute.

According to circumstance, the optical members 40 may include at leastone sheet, i.e., may selectively include a diffusion sheet, a prismsheet, a brightness enhancement sheet, etc.

Here, the diffusion sheet serves to diffuse light emitted by the lightsources, the prism sheet serves to guide diffused light to a lightemission area, and the brightness enhancement sheet serves to enhancebrightness of light.

Further, the stoppers 70 are disposed between the light source modules50 and the light guide plate 20, and serve to fix the light sourcemodules 50.

The stopper 70 may be disposed within the groove 24 of the light guideplate 20, and contact at least one of the side surface of the groove 24,the bottom surface of the groove 24 and the light source module 50.

Further, the stopper 70 may be disposed within the groove 24 of thelight guide plate 20, be separated from the side surface of the groove24 at a first interval, be separated from the bottom surface of thegroove 24 at a second interval, and be separated from the light sourcemodule 50 at a third interval.

Here, the interval between the side surface of the groove 24 and thestopper 70 may be greater than the interval between the bottom surfaceof the groove 24 and the stopper and the interval between the lightsource module 50 and the stopper 70, and the interval between the lightsource module 50 and the stopper 70 may be smaller than the intervalbetween the side surface of the groove 24 and the stopper 70 and thebottom surface of the groove 24 and the stopper 70.

The shape of the stoppers 70 may be varied according to the shape of thegrooves 24 of the light guide plate 20, and be formed of a polymer resinwhich enables injection molding.

For example, the stoppers 70 may be formed of at least one ofunsaturated polyester, methyl methacrylate, ethyl methacrylate, isobutylmethacrylate, n-butyl methacrylate, acrylic acid, methacrylic acid,hydroxyl ethyl methacrylate, hydroxyl propyl methacrylate, hydroxylethyl acrylate, acrylamide, ethyl acrylate, isobutyl acrylate andn-butyl acrylate.

The stoppers 70 are disposed within the grooves 24 of the light guideplate 20 within which the light source modules 50 are disposed, asdescribed above, thus serving to support the reflector 30 disposed onthe surfaces of the grooves 24 as well as to fix the light sourcemodules 50.

FIGS. 2 and 3 are cross-sectional views illustrating stoppers disposedwithin the grooves of the light guide plate. In more detail, FIG. 2 is across-sectional view illustrating a stopper contacting the groove of thelight guide plate, and FIG. 3 is a cross-sectional view illustrating astopper separated from the groove of the light guide plate.

As shown in FIG. 2, the stopper 70 is disposed within the groove 24 ofthe light guide plate 20, and may contact at least one of the sidesurface of the groove 24, the bottom surface of the groove 24 and thelight source module 50.

Here, if the reflector 30 is disposed on the side surface and the bottomsurface of the groove 24, the stopper 70 may contact the reflector 30.

Further, the stopper 70 may be separated from the light source 52 of thelight source module 50 at a designated interval, and partially contactthe upper surface and the side surface of the substrate 54 of the lightsource module 50.

As described above, the stopper 70 may contact both the reflector 30 andthe light source module 50 disposed within the groove 24 of the lightguide plate 20, or may contact either the reflector 30 or the lightsource module 50.

If the reflector 30 is not disposed within the groove 24 of the lightguide plate 20, the stopper 70 may contact all of the side surface ofthe groove 24, the bottom surface of the groove 24 and the light sourcemodule 50 or may contact at least one of the side surface of the groove24, the bottom surface of the groove 24 and the light source module 50.

As shown in FIG. 3, the stopper 70 is disposed within the groove 24 ofthe light guide plate 20. Here, the stopper 70 may be separated from theside surface of the groove 24 at a first interval d1, may be separatedfrom the bottom surface of the groove 24 at a second interval d2, may beseparated from the substrate 54 of the light source module 50 at a thirdinterval d3, and may be separated from the light source 52 of the lightsource module 50 by a fourth interval d4.

Here, the first interval d1 and the second interval d2 mean intervalsbetween the reflector 30 and the stopper 70 if the reflector 30 isdisposed within the groove 24 of the light guide plate 20.

The first interval d1, the second interval d2, the third interval d3 andthe fourth interval d4 may be equal, or at least one of the firstinterval d1, the second interval d2, the third interval d3 and thefourth interval d4 may differ from others.

For example, the first interval d1 between the side surface of thegroove 24 and the stopper 70 may be greater than the second interval d2between the bottom surface of the groove 24 and the stopper 70.

The reason for this is that, if the light guide plate 20 is thermallyexpanded, the side surface of the groove 24 opposite the stopper 70having a greater area than the bottom surface of the groove 24 oppositethe stopper 70 may be stretched much more than the bottom surface of thegroove 24.

The first interval d1 between the side surface of the groove 24 and thestopper 70 and the second interval d2 between the bottom surface of thegroove 24 and the stopper 70 may be greater than the third interval d3between the substrate 54 of the light source module 50 and the stopper70 and the fourth interval d4 between the light source 52 of the lightsource module 10 and the stopper 70.

The reason for this is that, if the light guide plate 20 is thermallyexpanded, the side surface and the bottom surface of the groove 24 maybe stretched.

Therefore, the first interval d1 may be greater than the second intervald2, the third interval d3 and the fourth interval d4, and the thirdinterval d3 and the fourth interval d4 may be smaller than the firstinterval d1 and the second interval d2.

According to circumstance, the third interval d3 may be smaller than thefourth interval d4.

The reason for this is that the light source 52 is sensitive to externalimpact, and thus maintenance of a designated interval between thestopper 70 and the light source 52 to prevent contact between thestopper 70 and the light source 52 is required.

Further, the stopper 70 may be attached to at least one of the lightsource module 50 and the light guide plate 20 by an adhesive agent.

FIGS. 4A to 4D are cross-sectional views illustrating stoppers attachedto the light source module and the light guide plate.

FIG. 4A illustrates an embodiment in which the stopper 70 is attached toa portion of the substrate 54 of the light source module 50 by anadhesive agent 75. As shown in FIG. 4A, the stopper 70 may be attachedto the upper surface of the substrate 54 of the light source module 50by the adhesive agent 75.

Further, the stopper 70 may be separated from the reflector 30 disposedwithin the groove 24 of the light guide plate 20 at a designatedinterval.

FIG. 4B illustrates an embodiment in which the stopper 70 is attached tothe substrate 54 of the light source module 50 by the adhesive agent 75.As shown in FIG. 4B, the stopper 70 may be attached to the upper surfaceand the side surface of the substrate 54 of the light source module 50by the adhesive agent 75.

Further, the stopper 70 may be separated from the reflector 30 disposedwithin the groove 24 of the light guide plate 20 at a designatedinterval.

Since the stopper 70 is attached to the upper surface and the sidesurface of the substrate 54 of the light source module 50 by theadhesive agent 75, the embodiment of FIG. 4B may be more stable than theembodiment of FIG. 4A in which the stopper 70 is attached only to theupper surface of the substrate 54 of the light source module 50.

FIG. 4C illustrates an embodiment in which the stopper 70 is attached tothe bottom surface of the groove 24 of the light guide plate 20 by theadhesive agent 75. As shown in FIG. 4C, the stopper 70 may be attachedto the bottom surface of the groove 24 of the light guide plate 20 orthe reflector 30 disposed on the bottom surface of the groove 24 of thelight guide plate 20 by the adhesive agent 75.

Here, the stopper 70 may be separated from the reflector 30 disposed onthe side surface of the groove 24 of the light guide plate 20 at adesignated interval, and may be separated from the light source 52 andthe substrate 54 of the light source module 50 at designated intervals.

FIG. 4D illustrates an embodiment in which the stopper 70 issimultaneously attached to the bottom surface of the groove 24 of thelight guide plate and the substrate 54 of the light source module 50 bythe adhesive agent 75. As shown in FIG. 4D, the stopper 70 may beattached to the bottom surface of the groove 24 of the light guide plate20 or the reflector 30 disposed on the bottom surface of the groove 24of the light guide plate 20, and to the upper surface and the sidesurface of the substrate 54 of the light source module 50, by theadhesive agent 75.

Here, the stopper 70 may be separated from the reflector 30 disposed onthe side surface of the groove 24 of the light guide plate 20 at adesignated interval.

Although the stopper 70 may be attached simultaneously to the substrate54 of the light source module 50 and the bottom surface of the groove 24of the light guide plate 20 using the same adhesive agent 75, asdescribed above, the stopper 70 may be attached to the substrate 54 ofthe light source module 50 and the bottom surface of the groove 24 ofthe light guide plate 20 using different adhesive agents 75.

That is, the stopper 70 may be attached to the substrate 4 of the lightsource module 54 by a first adhesive agent and be attached to the bottomsurface of the groove 24 of the light guide plate 20 by a secondadhesive agent, simultaneously.

Here, the first adhesive agent and the second adhesive agent may bedifferent materials, and each material may be at least one of epoxy anda silicon resin.

FIGS. 5A to 5C are cross-sectional views illustrating shapes of grooveson the light guide plate. FIGS. 5A and 5B are cross-sectional viewsillustrating grooves having different trapezoidal cross-sections, andFIG. 5C is a cross-sectional view illustrating a groove having atriangular cross-section.

As shown in FIGS. 5A to 5C, the groove 24 of the light guide plate 20may have various shapes. For example, the groove 24 of the light guideplate 20 may have a triangular, rectangular, or trapezoidalcross-section.

First, as shown in FIG. 5A, the groove 24 of the light guide plate 20has a trapezoidal cross-section.

Further, the groove 24 of the light guide plate 20 may include a firstside surface 24 a and a second side surface 24 c opposite each other,the first side surface 24 a of the groove 24 may be perpendicular to thebottom surface 24 b of the groove 24, and the second side surface 24 cof the groove 24 may be inclined with respect to the bottom surface 24 bof the groove 24.

The stopper 70 located within the groove 24 may include an inclinedsurface and a vertical surface identically with the shape of the groove24.

Further, the light source 52 located within the groove 24 may contactthe first side surface 24 a of the groove 24 perpendicular to the bottomsurface 24 b of the groove 24, or be separated from the first sidesurface 24 a at a designated interval.

Further, a light exit plane of the light source 52 faces the first sidesurface 24 a of the groove 24 so as to emit light towards the first sidesurface 24 a.

Next, as shown in FIG. 5B, the groove 24 of the light guide plate 20 hasanother trapezoidal cross-section.

Further, the groove 24 of the light guide plate 20 may include a firstside surface 24 a and a second side surface 24 c opposite each other,and the first side surface 24 a and the second side surface 24 c of thegroove 24 may be inclined with respect to the bottom surface 24 b of thegroove 24.

Here, an inclination angle θ1 between the first side surface 24 a andthe bottom surface 24 b of the groove 24 may be smaller than aninclination angle θ2 between the second side surface 24 c and the bottomsurface 24 b of the groove 24.

The stopper 70 located within the groove 24 may include an inclinedsurface identically with the shape of the groove 24.

Further, the light source 52 located within the groove 24 may partiallycontact the first side surface 24 a of the groove 24 inclined withrespect to the bottom surface 24 b of the groove 24, or be separatedfrom the first side surface 24 a at a designated interval.

Further, a light exit plane of the light source 52 faces the first sidesurface 24 a of the groove 24 so as to emit light towards the first sidesurface 24 a.

Next, as shown in FIG. 5C, the groove 24 of the light guide plate 20 hasa triangular cross-section.

Further, the groove 24 of the light guide plate 20 may include a firstside surface 24 a and a second side surface 24 c opposite each other,and an angle θ1 between the first side surface 24 a and the second sidesurface 24 c of the groove 24 may be about 30° to 120°

The stopper 70 located within the groove 24 may include a inclinedsurface identically with the shape of the groove 24.

The light source 52 located within the groove 24 may partially contactthe first side surface 24 a of the groove 24, or be separated from thefirst side surface 24 a at a designated interval.

Further, a light exit plane of the light source 52 faces the first sidesurface 24 a of the groove 24 so as to emit light towards the first sidesurface 24 a.

FIGS. 6A and 6B are cross-sectional views illustrating positionrelations between the groove of the light guide plate and the lightsource module.

FIG. 6A is a cross-sectional view illustrating position relationsbetween the groove 24 and the light source module 50 when the lightsource 52 of the light source module 50 contacts the light guide plate20, and FIG. 6B is a cross-sectional view illustrating positionrelations between the groove 24 and the light source module 50 when thelight source 52 of the light source module 50 is separated from thelight guide plate 20.

First, as shown in FIG. 6A, the groove 24 of the light guide plate 20may have a proper height D1 with respect to the overall thickness T1 ofthe light guide plate 20.

When the height D1 of the groove 24 of the light guide plate 20 isexcessively large, the light guide plate 20 may be damaged by externalimpact, and when the height D1 of the groove 24 of the light guide plate20 is excessively small, the overall thickness of the backlight unit maybe increased.

For example, a ratio of the height D1 of the groove 24 of the lightguide plate 20 to the overall thickness T1 of the light guide plate 20may be about 0.3˜0.7:1.

Further, a ratio of the height H1 of the light source module includingthe light source 52 and the substrate 54 to the height D1 of the groove24 of the light guide plate 20 may be about 0.5˜0.9:1.

When the height H1 of the light source module is excessively large, thelight source 52 may be damaged by thermal expansion of the light guideplate 20, and when the height H1 of the light source module isexcessively small, brightness of light may be lowered due to opticalloss.

First, as shown in FIG. 6B, the light source 52 of the light sourcemodule may be separated from the first side surface 24 a of the groove24 of the light guide plate 20 at a first interval D11, and be separatedfrom the second side surface 24 c of the groove 24 of the light guideplate 20 at a second interval D12.

Here, the second interval D12 is a distance from the end of the secondside surface 24 c adjacent to the bottom surface 24 b of the groove 24to one side surface of the light source 52.

Therefore, a ratio of the first interval D11 to the second interval D12may be 1:2˜50.

The reason for this is that a space to prevent damage to the lightsource 52 and a space to dispose the stopper 70 are required inconsideration of thermal expansion of the light guide plate 20.

As described above, the embodiments illustrate the stoppers disposedbetween the light guide plate and the light source modules, therebystabilizing the light source modules and thus improving reliability ofthe backlight unit.

FIG. 7 is a cross-sectional view illustrating a backlight unit inaccordance with another embodiment.

As shown in FIG. 7, the backlight unit includes stopper fastening parts26, a light guide plate 20, a reflector 30, optical members 40, lightsource modules 50, connection members 72 and stoppers 70.

The backlight unit may further include a top chassis 60, a bottomchassis 10, and a panel guide module 80.

Here, the panel guide module 80 may support a display panel 90, and thetop chassis 60 may be connected to the panel guide module 80 and thebottom chassis 10.

Then, at least one groove 24 may be disposed on the lower surface of thelight guide plate 20, and the optical members 40 may be disposed on theupper surface of the light guide plate 20.

Here, the grooves 24 of the light guide plate 20 may have a triangular,rectangular, or trapezoidal cross-section.

If the grooves 24 of the light guide plate 20 have a trapezoidalcross-section, from among first side surfaces and second side surfacesof the grooves 24 opposite each other, the first side surface of thegroove 24 may be perpendicular to the bottom surface of the groove 24,and the second side surface of the groove 24 may be inclined withrespect to the bottom surface of the groove 24.

Otherwise, if the grooves 24 of the light guide plate 24 have atrapezoidal cross-section, the first and second side surfaces of thegroove 24 opposite each other may be inclined with respect to the bottomsurface of the groove 24, and an angle between the first side surfaceand the bottom surface of the groove 24 may be smaller than an anglebetween the second side surface and the bottom surface of the groove 24.

Further, if the grooves 24 of the light guide plate 20 have a triangularcross-section, an angle between first and second side surfaces oppositeeach other of the groove 24 may be about 30° to 120°.

Further, a ratio of the height of the grooves 24 of the light guideplate 20 to the overall thickness of the light guide plate 20 may beabout 0.3˜0.7:1.

The light guide plate 20 may be formed of one selected from among thegroup consisting of acrylic resins, such as polymethylmethacrylate(PMMA), polyethylene terephthalate (PET), cyclic olefin copolymers(COCs), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene(PS) and methacrylate styrene (MS) resins.

The stopper fastening parts 26 may be disposed on the lower surface ofthe light guide plate 20.

Here, the stopper fastening parts 26 may be disposed on the lowersurface of the light guide plate 20 at positions adjacent to the grooves24 of the light guide plate 20.

The reason for this is that disposition of the stopper fastening parts26 adjacent to the grooves 24 of the light guide plate 20 serves tofacilitate connection to the connection members 72 contacting thestoppers 70 disposed within the grooves 24.

Further, the stopper fastening parts 26 may be disposed between thelight sources 52 of the light source module 50.

The reason for this is that, if the stopper fastening parts 26 aredisposed at dark regions between the light sources, light generated fromthe light sources are refracted by the stopper fastening parts 26 andthus the dark regions may be enhanced.

Therefore, the stopper fastening parts 26 contacting the light guideplate 20 may be projections protruding from the lower surface of thelight guide plate 20 or depressions disposed on the lower surface of thelight guide plate 20.

Further, the stopper fastening parts 26 may have one planar shape of acircle, a hemisphere, a triangle, a rectangle and a polygon.

The stopper fastening parts 26 may be formed integrally with the lightguide plate 20 using the same material as the light guide plate 20, ormay be formed of a material differing from the light guide plate 20.

Here, the stopper fastening parts 26 may be formed of one selected fromamong the group consisting of polymethylmethacrylate (PMMA),polyethylene terephthalate (PET), cyclic olefin copolymers (COCs),polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS) andmethacrylate styrene (MS) resins.

The light source modules 50 may be disposed within the grooves 24 of thelight guide plate 20.

Here, each light source module 50 may include a substrate 54 and atleast one light source 52 disposed on the substrate 54. Both thesubstrate 54 and the at least one light source 52 may be disposed withinthe groove 24 of the light guide plate 20.

According to circumstance, the substrate 54 may be disposed at theoutside of the groove 24 of the light guide plate 20, and the at leastone light source 52 may be disposed within the groove 24 of the lightguide plate 20.

The at least one light source 52 may be disposed on the substrate 54,and the light source 52 may be a side view type LED

According to circumstance, the light source 52 may be a top view typeLED.

The reflector 30 may be disposed on the lower surface of the light guideplate 20.

That is, the reflector 30 may be disposed between the light guide plate20 and the bottom chassis 10, and may extend from the lower surface tothe side surface of the light guide plate 20.

Although this embodiment describes the reflector 30 as not beingdisposed on the lower surface of the substrate 54 of the light sourcemodule 50, the reflector 30 may be disposed on the lower surface of thesubstrate 54 of the light source module, according to circumstance.

Further, the reflector 30 may be disposed on at least one of the sidesurface and the bottom surface of the groove 24 of the light guide plate20.

Here, the reflector 30 may be formed of at least one of a metal and ametal oxide, and for example, may be formed of a metal or a metal oxideexhibiting high reflectivity, such as aluminum (Al), silver (Ag), gold(Au) or titanium oxide (TiO₂).

The optical members 40 are disposed on the upper surface of the lightguide plate 20.

Here, the optical members 40 serve to improve optical characteristics oflight emitted through the light guide plate 20, and may have an unevenpattern disposed on the upper surface thereof.

Further, the stoppers 70 are disposed between the light source modules50 and the light guide plate 20, and serve to fix the light sourcemodules 50.

The stopper 70 may be disposed within the groove 24 of the light guideplate 20, and contact at least one of the side surface of the groove 24,the bottom surface of the groove 24 and the light source module 50.

Further, the stopper 70 may be disposed within the groove 24 of thelight guide plate 20, be separated from the side surface of the groove24 at a first interval, be separated from the bottom surface of thegroove 24 at a second interval, and be separated from the light sourcemodule 50 at a third interval.

Here, the interval between the side surface of the groove 24 and thestopper 70 may be greater than the interval between the bottom surfaceof the groove 24 and the stopper and the interval between the lightsource module 50 and the stopper 70, and the interval between the lightsource module 50 and the stopper 70 may be smaller than the intervalbetween the side surface of the groove 24 and the stopper 70 and thebottom surface of the groove 24 and the stopper 70.

The shape of the stoppers 70 may be varied according to the shape of thegrooves 24 of the light guide plate 20, and be formed of a polymer resinwhich enables injection molding.

For example, the stoppers 70 may be formed of at least one ofunsaturated polyester, methyl methacrylate, ethyl methacrylate, isobutylmethacrylate, n-butyl methacrylate, acrylic acid, methacrylic acid,hydroxyl ethyl methacrylate, hydroxyl propyl methacrylate, hydroxylethyl acrylate, acrylamide, ethyl acrylate, isobutyl acrylate andn-butyl acrylate.

The stoppers 70 are disposed within the grooves 24 of the light guideplate 20 within which the light source modules 50 are disposed, asdescribed above, thus serving to support the reflector 30 disposed onthe surfaces of the grooves 24 as well as to fix the light sourcemodules 50.

The connection member 72 contacting the stopper 70 may include a bodyportion 72 a and a connection portion 72 b.

Here, the body portion 72 a may support the stopper 70 and the substrate54 of the light source module 50, and the connection portion 72 b mayprotrude from the body portion 72 a and be connected to the stopperfastening part 26 contacting the light guide plate 20.

FIGS. 8 and 9 are cross-sectional views illustrating stoppers disposedwithin the grooves of the light guide plate. That is, FIG. 8 is across-sectional view illustrating a stopper contacting the groove of thelight guide plate, and FIG. 9 is a cross-sectional view illustrating astopper separated from the groove of the light guide plate.

As shown in FIG. 8, the stopper 70 may be disposed within the groove 24of the light guide plate 20, and contact at least one of the sidesurface of the groove 24, the bottom surface of the groove 24 and thelight source module 50.

Here, if the reflector 30 is disposed on the side surface and the bottomsurface of the groove 24, the stopper 70 may contact the reflector 30.

Further, the stopper 70 may be separated from the light source 52 of thelight source module 50 at a designated interval, and partially contactthe upper surface and the side surface of the substrate 54 of the lightsource module 50.

As described above, the stopper 70 may contact both the reflector 30 andthe light source module 50 disposed within the groove 24, or may contacteither the reflector 30 or the light source module 50.

If the reflector 30 is not disposed within the groove 24 of the lightguide plate 20, the stopper 70 may contact all of the side surface ofthe groove 24, the bottom surface of the groove 24 and the light sourcemodule 50 or may contact at least one of the side surface of the groove24, the bottom surface of the groove 24 and the light source module 50.

The connection member 72 contacting the stopper 70 may include a bodyportion 72 a and a connection portion 72 b. The body portion 72 a maysupport the stopper 70 and the substrate 54 of the light source module50, and the connection portion 72 b may protrude from the body portion72 a and be connected to the stopper fastening part 26 contacting thelight guide plate 20.

As shown in FIG. 9, the stopper 70 which is disposed within the groove24 of the light guide plate 20 may be separated from the side surface ofthe groove 24 at a first interval d1, may be separated from the bottomsurface of the groove 24 at a second interval d2, may be separated fromthe substrate 54 of the light source module 50 at a third interval d3,and may be separated from the light source 52 of the light source module50 by a fourth interval d4.

Here, the first interval d1 and the second interval d2 mean intervalsbetween the reflector 30 and the stopper 70 if the reflector 30 isdisposed within the groove 24 of the light guide plate 20.

The first interval d1, the second interval d2, the third interval d3 andthe fourth interval d4 may be equal, or at least one of the firstinterval d1, the second interval d2, the third interval d3 and thefourth interval d4 may differ from others.

For example, the first interval d1 between the side surface of thegroove 24 and the stopper 70 may be greater than the second interval d2between the bottom surface of the groove 24 and the stopper 70.

The reason for this is that, if the light guide plate 20 is thermallyexpanded, the side surface of the groove 24 opposite the stopper 70having a greater area than the bottom surface of the groove 24 oppositethe stopper 70 may be stretched much more than the bottom surface of thegroove 24.

The first interval d1 between the side surface of the groove 24 and thestopper 70 and the second interval d2 between the bottom surface of thegroove 24 and the stopper 70 may be greater than the third interval d3between the substrate 54 of the light source module 50 and the stopper70 and the fourth interval d4 between the light source 52 of the lightsource module 10 and the stopper 70.

The reason for this is that if the light guide plate 20 is thermallyexpanded, the side surface and the bottom surface of the groove 24 maybe stretched.

Therefore, the first interval d1 may be greater than the second intervald2, the third interval d3 and the fourth interval d4, and the thirdinterval d3 and the fourth interval d4 may be smaller than the firstinterval d1 and the second interval d2.

According to circumstance, the third interval d3 may be smaller than thefourth interval d4.

The reason for this is that the light source 52 is sensitive to externalimpact, and thus maintenance of a designated interval between thestopper 70 and the light source 52 to prevent contact between thestopper 70 and the light source 52 is required.

Further, the stopper 70 may be attached to at least one of the lightsource module 50 and the light guide plate 20 by an adhesive agent.

The connection member 72 contacting the stopper 70 may include a bodyportion 72 a and a connection portion 72 b. The body portion 72 a maysupport the stopper 70 and the substrate 54 of the light source module50, and the connection portion 72 b may protrude from the body portion72 a and be connected to the stopper fastening part 26 contacting thelight guide plate 20.

FIG. 10 is a structural cross-sectional view illustrating connectionbetween a connection member contacting a stopper and a stopper fasteningpart contacting a light guide plate in accordance with a firstembodiment, FIG. 11A is a bottom perspective view illustrating thestopper fastening part of FIG. 10, FIG. 11B is a bottom perspective viewillustrating the connection member of FIG. 10, and FIG. 11C is a bottomperspective view illustrating connection between the connection memberand the stopper fastening part of FIG. 10.

As shown in FIGS. 10 and 11A, the stopper fastening part 26 connected tothe connection member 72 contacting the stopper 70 may be disposed onthe lower surface of the light guide plate 20.

The stopper fastening part 26 may be a projection disposed at a positionadjacent to the groove of the light guide plate 20 and protruding fromthe lower surface of the light guide plate 20.

Here, the stopper fastening part 26 may have a rectangular planar shape,or may have various planar shapes of a circle, a hemisphere, a triangleand a polygon.

Further, the stopper fastening part 26 may be formed in an integral typeformed of the same material as the light guide plate 20, or may beformed in a separate type formed of a material differing from the lightguide plate 20.

The thickness t1 of the stopper fastening part 26 may be equal to thatof the connection member 72 contacting the stopper 70.

Further, the side surface of the stopper fastening part 26 and the sidesurface of the groove of the light guide plate 20 may be located on thesame plane so as not to deviate from each other.

Next, as shown in FIGS. 10 and 11B, the connection member 72 may bedisposed under the stopper 70 and be connected to the stopper fasteningpart 26 contacting the light guide plate 20.

Here, the connection member 72 contacting the stopper 70 may include abody portion 72 a and a connection portion 72 b.

The body portion 72 a may support the stopper 70 and the substrate 54 ofthe light source module 50, and the connection portion 72 b may protrudefrom the body portion 72 a and be connected to the stopper fasteningpart 26 contacting the light guide plate 20.

Here, the connection portion 72 b may include a first segment 72 b 2 anda second segment 72 b 1.

The first segment 72 b 2 may protrude from the body portion 72 a in afirst direction, and the second segment 72 b 1 may be bent from the endof the first segment 72 b 2 in a second direction perpendicular to thefirst direction.

Here, the thickness of the first segment 72 b 2 may be equal to thethickness t2 of the body portion 72 a and the thickness t3 of the secondsegment 72 b 1.

Further, the width W1 of the first segment 72 b 2 may be equal to thewidth W2 of the second segment 72 b 1, or may differ from the width W2of the second segment 72 b 1 according to circumstance.

Next, as shown in FIGS. 10 and 11C, the connection member 72 may includeat least one connection portion 72 b, and one connection portion 72 bmay be connected to one stopper fastening part 26 one to one.

Here, the first segment 72 b 2 of the connection portion 72 b maycontact a first side surface of the stopper fastening part 26, and thesecond segment 72 b 1 of the connection portion 72 b may contact asecond side surface of the stopper fastening part 26.

Further, as shown in FIG. 10, a side surface 54 a of the substrate 54 ofthe light source module 50 may contact the side surface of the lightguide plate 20, or may be separated from the side surface of the lightguide plate 20.

FIG. 12 is a structural cross-sectional view illustrating connectionbetween a connection member contacting a stopper and a stopper fasteningpart contacting a light guide plate in accordance with a secondembodiment, FIG. 13A is a bottom perspective view illustrating theconnection member of FIG. 12, and FIG. 13B is a structuralcross-sectional view illustrating the connection member of FIG. 13A.

Stopper fastening parts 26 contacting stoppers 70 in the secondembodiment are the same as those in the first embodiment, and a detaileddescription thereof will thus be omitted.

As shown in FIG. 12 and FIGS. 13A and 13B, a connection member 72 may bedisposed under the stopper 70 and be connected to the stopper fasteningpart 26 contacting the light guide plate 20.

Here, the connection member 72 contacting the stopper 70 may include abody portion 72 a and a connection portion 72 b.

The body portion 72 a may support the stopper 70 and the substrate 54 ofthe light source module 50, and the connection portion 72 b may protrudefrom the body portion 72 a and be connected to the stopper fasteningpart 26 contacting the light guide plate 20.

Here, the connection portion 72 b may include a first segment 72 b 2 anda second segment 72 b 1.

The first segment 72 b 2 may protrude from the body portion 72 a in afirst direction, and the second segment 72 b 1 may be bent from the endof the first segment 72 b 2 in a second direction perpendicular to thefirst direction.

Here, the thickness t31 of the first segment 72 b 2 may be greater thanthe thickness t2 of the body portion 72 a and be equal to the thicknesst32 of the second segment 72 b 1.

Further, the connection member 72 may include at least one connectionportion 72 b, and one connection portion 72 b may be connected to onestopper fastening part 26 one to one.

Here, the first segment 72 b 2 of the connection portion 72 b maycontact a first side surface of the stopper fastening part 26, and thesecond segment 72 b 1 of the connection portion 72 b may contact asecond side surface of the stopper fastening part 26.

Further, as shown in FIG. 12, a side surface 54 a of the substrate 54 ofthe light source module 50 may contact the side surface of the stopperfastening part 26 contacting the light guide plate 20, or may beseparated from the side surface of the stopper fastening part 26.

The thickness t1 of the stopper fastening part 26 may be greater thanthe thickness t2 of the body portion 72 a of the connection member 72contacting the stopper 70 and be equal to the thickness t3 of theconnection portion 72 b of the connection member 72.

FIG. 14 is a structural cross-sectional view illustrating connectionbetween a connection member contacting a stopper and a stopper fasteningpart contacting a light guide plate in accordance with a thirdembodiment, FIG. 15A is a bottom perspective view illustrating theconnection member of FIG. 14, and FIG. 15B is a structuralcross-sectional view illustrating the connection member of FIG. 15A.

Stopper fastening parts 26 contacting a light guide plate 20 in thethird embodiment are the same as those in the first embodiment, and adetailed description thereof will thus be omitted.

As shown in FIG. 14 and FIGS. 15A and 15B, a connection member 72 may bedisposed under a stopper 70 and be connected to the stopper fasteningpart 26 contacting the light guide plate 20.

Here, the connection member 72 contacting the stopper 70 may include abody portion 72 a and a connection portion 72 b.

The body portion 72 a may support the stopper 70 and the substrate 54 ofthe light source module 50, and the connection portion 72 b may protrudefrom the body portion 72 a and be connected to the stopper fasteningpart 26 contacting the light guide plate 20.

Here, the connection portion 72 b may include a first segment 72 b 2 anda second segment 72 b 1.

The first segment 72 b 2 may protrude from the body portion 72 a in afirst direction, and the second segment 72 b 1 may be bent from the endof the first segment 72 b 2 in a second direction perpendicular to thefirst direction.

Here, the thickness t31 of the first segment 72 b 2 may be greater thanthe thickness t2 of the body portion 72 a and be greater than thethickness t32 of the second segment 72 b 1.

According to circumstance, the thickness t32 of the second segment 72 b1 may be equal to the thickness t2 of the body portion 72 a.

Further, the connection member 72 may include at least one connectionportion 72 b, and one connection portion 72 b may be connected to onestopper fastening part 26 one to one.

Here, the first segment 72 b 2 of the connection portion 72 b maycontact a first side surface of the stopper fastening part 26, and thesecond segment 72 b 1 of the connection portion 72 b may contact asecond side surface of the stopper fastening part 26.

Further, as shown in FIG. 14, a side surface 54 a of the substrate 54 ofthe light source module 50 may contact the side surface of the stopperfastening part 26 contacting the light guide plate 20, or may beseparated from the side surface of the stopper fastening part 26.

The thickness t1 of the stopper fastening part 26 may differ from thethickness t2 of the body portion 72 a of the connection member 72contacting the stopper 70 and the thickness t3 of the connection portion72 b of the connection member 72.

FIG. 16A is a bottom perspective view illustrating a stopper fasteningpart contacting a light guide plate in accordance with a fourthembodiment, FIG. 16B is a bottom perspective view illustrating aconnection member contacting a stopper in accordance with the fourthembodiment, and FIG. 16C is a bottom perspective view illustratingconnection between the connection member contacting the stopper and thestopper fastening part contacting the light guide plate in accordancewith the fourth embodiment.

As shown in FIGS. 16A to 16C, a connection member 72 may be disposedunder a stopper 70 and be connected to a stopper fastening part 26contacting a light guide plate 20.

Here, the connection member 72 contacting the stopper 70 may include abody portion 72 a and connection portions 72 b.

The body portion 72 a may support the stopper 70 and the substrate 54 ofthe light source module 50, and the connection portions 72 b mayprotrude from the body portion 72 a and be connected to the stopperfastening part 26 contacting the light guide plate 20.

Here, a plurality of connection portions 72 b may be provided, and apair of connection portions 72 b may be provided such that the twoconnection portions 72 b are disposed between adjacent stopper fasteningparts 26.

That is, the connection member 72 contacting the stopper 70 inaccordance with the fourth embodiment may include a pair of connectionportions 72 b formed in an arrow shape, and the pair of connectionprotrusions 72 b may be disposed between the stopper fastening parts 26contacting the light guide plate 20.

Here, one corner area of each of the stopper fastening parts 26contacting the light guide plate 20 is inclined, and thus the pair ofconnection portions 72 b may be easily fastened to the stopper fasteningparts 26 contacting the light guide plate 20.

FIG. 17A is a bottom perspective view illustrating a stopper fasteningpart contacting a light guide plate in accordance with a fifthembodiment, FIG. 17B is a bottom perspective view illustrating aconnection member contacting a stopper in accordance with the fifthembodiment, and FIG. 17C is a bottom perspective view illustratingconnection between the connection member contacting the stopper and thestopper fastening part contacting the light guide plate in accordancewith the fifth embodiment.

As shown in FIGS. 17A to 17C, a connection member 72 may be disposedunder a stopper 70 and be connected to a stopper fastening part 26contacting a light guide plate 20.

Here, the stopper fastening part 26 contacting the light guide plate 20may be a depression 25 disposed on the lower surface of the light guideplate 20 and having a designated height t5.

Here, the depression 25 may have at least one planar shape of a circle,a hemisphere, a triangle, a rectangle and a polygon.

Further, the connection member 72 contacting the stopper 70 may includea body portion 72 a and a connection portion 72 b.

The body portion 72 a may support the stopper 70 and the substrate 54 ofthe light source module 50, and the connection portion 72 b may protrudefrom the body portion 72 a and be connected to the stopper fasteningpart 26 contacting the light guide plate 20.

Here, the connection portion 72 b may include a first segment 72 b 2 anda second segment 72 b 1, and the first segment 72 b 2 may protrude fromthe body portion 72 a.

Further, the second segment 72 b 1 may extend from the end of the firstsegment 72 b 2 and have a greater area than the first segment 72 b 2.

The planar shapes of the first and second segments 72 b 2 and 72 b 1 maybe equal to the planar shape of the stopper fastening part 26 of thelight guide plate 20.

FIG. 18 is a plan view illustrating an area in which a stopper fasteningpart contacting a light guide plate in accordance with one embodiment isdisposed.

As shown in FIG. 18, a stopper fastening part 26 contacting a lightguide plate 20 may be located on the lower surface of the light guideplate 20, and may be disposed at a position adjacent to a light sourcemodule 50 disposed within a groove of the light guide plate 20.

That is, the stopper fastening part 26 may be disposed opposite asubstrate 54 of the light source module 50 disposed within the groove ofthe light guide plate 20.

Further, the stopper fastening part 26 may be disposed at a positioncorresponding to a region between light sources 52 of the light sourcemodule 50.

The reason why the stopper fastening part 26 is disposed between thelight sources 52 is that, when adjacent light sources 52 are separatedfrom each other at a designated interval, a dark region may be generatedbetween the light sources 52 due to light spreading.

Therefore, as shown in FIG. 18, if the stopper fastening part 26 isdisposed on the lower surface of the light guide plate 20 between thelight sources 52, light is refracted by the stopper fastening part 26having the shape of a projection or a depression, and thus generation ofa dark region between the light sources 52 may be reduced.

As described above, the embodiments describe the stoppers as beingdisposed between the light guide plate and the light source modules andas being stably fastened to the light guide plate, thereby stabilizingthe light source modules and thus improving reliability of the backlightunit.

FIG. 19 is a cross-sectional view illustrating a display module having abacklight unit in accordance with one embodiment.

As shown in FIG. 19, a display module 200 includes a display panel 90and a backlight unit 100.

The display panel 90 includes a color filter substrate 91 and a thinfilm transistor (TFT) substrate 92 disposed opposite each other andbonded to each other to maintain a uniform cell gap, and a liquidcrystal layer (not shown) may be interposed between the two substrates91 and 92.

The color filter substrate 91 includes a plurality of pixels includingred (R), green (G) and blue (B) sub-pixels, and generates an imagecorresponding to red, green or blue if light is applied to the colorfilter substrate 91.

Although the pixels may include red (R), green (G) and blue (B)sub-pixels, the embodiment is not limited thereto and red (R), green(G), blue (B) and white (W) sub-pixels may form one pixel.

The TFT substrate 92 includes switching elements, and may switch pixelelectrodes (not shown).

For example, a common electrode (not shown) and the pixel electrodes maychange arrangement of molecules of the liquid crystal layer based on adesignated voltage applied from the outside.

The liquid crystal layer may include a plurality of liquid crystalmolecules, and arrangement of the liquid crystal molecules is changeddue to a voltage difference between the pixel electrodes and the commonelectrode.

Thereby, light generated from the backlight unit 100 may be incidentupon the color filter substrate 90 in response to change of moleculararrangement of the liquid crystal layer.

Further, an upper polarizing plate 93 and a lower polarizing plate 94may be disposed on the upper surface and the lower surface of thedisplay panel 90, and more particularly, the upper polarizing plate 93may be disposed on the upper surface of the color filter substrate 91and the lower polarizing plate 94 may be disposed on the lower surfaceof the TFT substrate 92.

Although not shown in the drawings, gate and data driving unitsgenerating driving signals to drive the display panel 90 may be providedon the side surface of the display panel 90.

As shown in FIG. 19, the display module 200 may be formed by disposingthe backlight unit 100 close to the display panel 90.

For example, the backlight unit 100 may be fixed to the lower surface ofthe display panel 90, more particularly be attached to the lowerpolarizing plate 94, and for this purpose, an adhesive layer (not shown)may be formed between the lower polarizing plate 94 and the backlightunit 100.

By attaching the backlight unit 100 to the display panel 90, asdescribed above, the overall thickness of the display apparatus isreduced, and thus the external appearance of the display apparatus maybe improved. Further, additional structures to fix the backlight unit100 are removed, and thus the structure and manufacturing process of thedisplay apparatus may be simplified.

Further, by removing a space between the backlight unit 100 and thedisplay panel 90, malfunction of the display apparatus or deteriorationof the quality of a displayed image due to invasion of foreignsubstances into the space may be prevented.

FIGS. 20 and 21 are views respectively illustrating display apparatusesin accordance with embodiments.

First, as shown in FIG. 20, a display apparatus 1 includes a displaymodule 200, a front cover 300 and a back cover 350 surrounding thedisplay module 200, a driving unit 550 provided on the back cover 350,and a driving unit cover 400 surrounding the driving unit 550.

The front cover 300 may include a front panel (not shown) formed of atransparent material transmitting light. The front panel which isseparated from the display module 200 at a designated interval protectsthe display module 200 and transmits light emitted from the displaymodule 200, thereby allowing an image displayed on the display module200 to be seen from the outside.

Further, the front cover 300 may be a flat plate without a window 300 a.

In this case, the front cover 300 may be formed of a transparentmaterial transmitting light, for example, of injection molded plastic.

If the front cover 300 is a flat plate, a frame may be removed from thefront cover 300.

The back cover 350 may be connected to the front cover 300 to protectthe display module 200.

The driving unit 550 may be disposed on one surface of the back cover350.

The driving unit 550 may include a driving control unit 550 a, a mainboard 550 b and a power supply unit 550 c.

The driving control unit 550 a may be a timing controller, i.e., adriver to control operation timing of respective driver ICs of thedisplay module 200, the main board 550 b may be a driver to transmit aV-sync, an H-sync and R, G and B resolution signals to the timingcontroller, and the power supply unit 550 c may be a driver to applypower to the display module 200.

The driving unit 550 may be provided on the back cover 350 and besurrounded by the driving unit cover 400.

The back cover 350 may be provided with a plurality of holes throughwhich the display module 200 and the driving unit 550 are connected toeach other, and a stand 600 to support the display apparatus 1 may beprovided.

Next, as shown in FIG. 21, the driving control unit 550 a of the drivingunit 550 may be provided on the back cover 350, and the main board 550 band the power supply unit 550 c of the driving unit 550 may be providedon the stand 600.

Further, the driving unit cover 400 may surround only the drivingcontrol unit 550 a provided on the back cover 350.

Although the embodiments describe the main board 550 b and the powersupply unit 550 c as being separately provided, the main board 550 b andthe power supply unit 550 c may be integrated into one board.

Another embodiment may implement a display apparatus, an indicationapparatus or an illumination system including the stoppers, the stopperfastening units, the light guide plate having the grooves, and the lightsource modules described in accordance with the above-describedembodiments, and, for example, the illumination system may include alamp or a streetlight.

Such an illumination system may be used as an illumination lamp whichconcentrates light emitted from plural LEDs, particularly used as a lamp(down light) which is embedded in the ceiling or the wall of a buildingand is installed to expose an opening of a shade.

As is apparent from the above description, a backlight unit and adisplay apparatus using the same in accordance with one embodiment formstoppers between a light guide plate and light source modules and fastenstoppers to the light guide plate, thereby stabilizing the light sourcemodules and thus improving reliability of the backlight unit.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. An illumination system, comprising: a light guideplate; grooves disposed in the light guide plate, each of the grooveshaving at least one inclined surface; light source modules disposedwithin the grooves, wherein the light source modules comprise:substrates; and light sources disposed on the substrates; and stoppersdisposed between a first surface of each of the light sources and the atleast one inclined surface of each of the grooves, the first surface ofeach of the light sources facing the at least one inclined surface,wherein a cross-sectional area of the grooves is larger than that of thestoppers.
 2. The illumination system according to claim 1, wherein thestoppers contact at least one of the side surfaces of the grooves, thebottom surfaces of the grooves and the light source modules.
 3. Theillumination system according to claim 1, wherein the stoppers areseparated from the side surfaces of the grooves at a first interval, areseparated from the bottom surfaces of the grooves at a second interval,and are separated from the light source modules by a third interval. 4.The illumination system according to claim 3, wherein the first intervalis greater than the second and third intervals, and the third intervalis smaller than the first and second intervals.
 5. The illuminationsystem according to claim 1, wherein the stoppers are attached to thesubstrates of the light source modules by an adhesive agent.
 6. Theillumination system according to claim 1, wherein the stoppers areattached to the bottom surfaces of the grooves of the light guide plateby an adhesive agent.
 7. The illumination system according to claim 1,wherein the stoppers are simultaneously attached to the substrates ofthe light source modules by a first adhesive agent and the bottomsurfaces of the grooves of the light guide plate by a second adhesiveagent.
 8. The illumination system according to claim 7, wherein thefirst adhesive agent and the second adhesive agent are integrallyformed.
 9. The illumination system according to claim 7, wherein thefirst adhesive agent and the second adhesive agent are formed ofdifferent materials.
 10. The illumination system according to claim 1,wherein a reflector is disposed on at least one of the side surfaces orthe bottom surfaces of the grooves of the light guide plate.
 11. Theillumination system according to claim 1, wherein a reflector isdisposed between the stoppers and top surfaces of the grooves of thelight guide plate.
 12. The illumination system according to claim 11,wherein the reflector directly contacts the stoppers.
 13. Theillumination system according to claim 11, wherein the reflector isseparated from the stoppers.
 14. The illumination system according toclaim 11, wherein the stoppers are attached to the reflector by anadhesive agent.
 15. The illumination system according to claim 11,wherein the reflector is further disposed between the top surfaces ofthe grooves of the light guide plate and a second surface of each of thelight sources, the second surface being perpendicular to the firstsurface of each of the light sources.
 16. The illumination systemaccording to claim 1, wherein a reflector is disposed on lower surfacesof the substrates.
 17. The illumination system according to claim 1,wherein the substrates and the stoppers are disposed within the grooves.18. The illumination system according to claim 1, wherein the substratesare disposed at outside of the grooves.
 19. A display apparatus,comprising: a display panel; and an illumination system irradiatinglight onto the display panel, wherein the illumination system includes:a light guide plate having grooves, each of the grooves having at leastone inclined surface; light source modules disposed within the groovesof the light guide plate, wherein the light source modules comprise:substrates; light sources disposed on the substrates; and stoppersdisposed between a first surface of each of the light source modules andthe at least one inclined surface of each of the grooves, the firstsurface of each of the light sources facing the at least one inclinedsurface, wherein a cross-sectional area of the grooves is larger thanthat of the stoppers, and
 20. The display apparatus according to claim19, wherein the substrates and the stoppers are disposed within thegrooves.